As a result of recent trend for finer design of wiring patterns, requirement is made of an improvement in in-plane uniformity of coverage. As a method of materializing this kind of requirements, it is known to use a DC magnetron sputtering apparatus which utilizes the art of, e.g., self-ionized plasma (SIP). According to the SIP art, by charging a high potential in a magnetic field which is high in electron containment capacity, high-density plasma is materialized.
As an apparatus for stably performing the above-mentioned self sputtering, the following art is known in Patent Document 1. That is, in addition to forming a magnetic field in front of a sputtering surface of a target by disposing a magnet assembly on a side opposite to the sputtering surface of the target, there is disposed a coil on the side surface of the vacuum chamber. By charging electric power to the coil through a power supply for the coil, a magnetic field vertical to the sputtering surface is generated. The ionization of the atoms scattered from the target will thus be accelerated.
However, in the above-mentioned apparatus described in Patent Document 1, the electric power supply is separately provided for charging the coil with electric power. Therefore, there is a problem in that the cost of the sputtering apparatus becomes higher. In addition, in order to adjust the direction of the magnetic field or the intensity of the magnetic field, there will be needed an electric current control circuit for controlling the electric current to be charged to coil, thereby bringing about a further increase in cost.    Patent Document 1: JP-A-2000-144411